1. Technical Field
Embodiments of the present disclosure relate to the field of image measurement, and more particularly to a system and method for automatically focusing an optical lens of an image measuring machine.
2. Description of Related Art
A charged coupled device (CCD) is an electrical device that is used to capture images of objects, store information (analogous to the way a computer stores information), or transfer electrical charge (as part of a larger device). CCDs are used in a variety of different imaging devices, such as imagers, CCD cameras or scanners. CCDs are only part of the whole device. To capture images of an object, an optical lens needs to be properly focused on the object.
One such image measuring machine includes a focusing apparatus for adjusting the optical lens to focus on the object, so as to obtain clear digital images of the object for measurement. Generally, a user determines a focus of the optical lens according to the gray value of the captured digital image of the object. However, if the surface of the object is very smooth, the captured digital images will not be clear. As a result, the precision of focusing will directly be affected, which wastes time and reduces productivity.
Therefore, there is a need for a system and method to overcome the aforementioned problem.